A clinical evaluation of blood pressure through non-invasive measurement using the oscillometric procedure in conscious dogs

Impact of equipment and handling on systolic blood pressure measurements in conscious dogs in an animal hospital environment

Background

Situational hypertension and differences between devices complicate interpretations of systolic blood pressure (SBP) measurements in dogs.

Hypothesis/Objectives

To evaluate if time point of in‐clinic SBP measurement, type of oscillometric device, and operator affect SBP measurements in conscious dogs.

Animals

Sixty‐seven privately owned dogs with or without chronic kidney disease, divided into 2 study samples (A and B).

Methods

Cross‐sectional diagnostic study. In part A, SBP measurements in dogs were performed using 2 different devices (HDO and petMap) after acclimatization at 3 standardized time points during a clinical visit. In part B, SBP measurements (HDO) were performed in dogs by a trained final year veterinary student and by the owner alone, at the same occasion.

Results

For all dogs, there was no difference in mean SBP (mSBP) among the 3 time points for HDO (P = .12) or petMAP (P = .67). However, intraindividual mSBP differences of up to 60 mm Hg between time points were documented. Mean SBP obtained with petMAP was on average 14 (95% CI: 8‐20) mm Hg higher than mSBP obtained with HDO, and this difference increased with increasing SBP. Mean SBP measurements obtained by the trained student were 7 (95% CI: 2‐11) mm Hg higher than mSBP measurements obtained by the owner.

Conclusions and Clinical Importance

According to the results of this study, time point of in‐clinic SBP measurement in dogs is of minor importance, and instructing owners to perform measurements might reduce suspected situational hypertension. Differences in mSBP measured with HDO and petMAP underscore the need for validation of BP devices used clinically.

Blood pressure and renal injury in dogs with visceral leishmaniasis

Abstract: Systemic hypertension is known to be a common consequence of chronic renal disease, which is frequently diagnosed in dogs with visceral leishmaniasis. Although many veterinary investigations have looked at the renal injury caused by Leishmania spp., the role played by this complication in the development of arterial hypertension documented in some animals with visceral leishmaniasis is not completely understood. In this study, 18 adult dogs with naturally-occurring visceral leishmaniasis and varying clinical signs underwent an indirect blood pressure measurement. Also, sera and spot urine were used for laboratory tests. The median systolic blood pressure was 135.2mmHg (95% confidence interval: 128.5-147.7), median mean arterial pressure was 105.8mmHg (98.3-110.4), and median diastolic arterial pressure was 88.5mmHg (77.8-92.5). No differences existed between asymptomatic and symptomatic animals regarding arterial pressure, and no correlations were documented between blood pressure and serum creatinine, blood urea, urine protein-to-creatinine ratio, urine specific gravity, and the fractional excretion of sodium and potassium. Although an association between hypertension and the identification of inflammation on histopathology could not be demonstrated in hypertensive animals, the assessment of kidney samples from 12 dogs indicated mild inflammation with a lymphoplasmacytic infiltrate (6/12), moderate inflammation with multifocal lymphoplasmacytic and histiocytic infiltrates (3/12), and multifocal degeneration and protein casts (2/12). Anti-Leishmania spp. immunohistochemistry assays stained the renal epithelium in 2/12 of the animals. Even though mild systemic hypertension was documented in a small subset of animals, no relationship between the severity of clinical signs and hypertension could be anticipated.

Obesity-hypertension and its relation to other diseases in dogs

Obesity is a chronic disease in which adipose tissue accumulates in such a way that it affects the health of the patient and is associated with a myriad of alterations such as systemic hypertension (HTN). The mechanisms by which obesity causes HTN are complex and involve several organic mechanisms. The objective of this study was to determine the correlation between obesity to HTN in dogs in accordance with recent international protocols (systolic blood pressure >160 mmHg) relating to age, genre, gonadal status, breed and other diseases commonly associated with HTN. A total of 244 dogs were studied, 105 non-obese controls and 139 in the obese group. For both groups, healthy and a variety of diseased dogs were observed; the correlations between pathologies and obesity were studied, paying special attention to diseases whose pathophysiologies could lead to HTN. We conclude that obesity is not a risk factor for dogs to develop HTN, and that HTN present in these patients was related to comorbidities such as chronic kidney disease, cardiopathies and endocrinopathies.

Comparison of noninvasive blood pressure measurement techniques via the coccygeal artery in anesthetized cheetahs (Acinonyx jubatus)

Two indirect blood pressure measurement techniques, Doppler (DOP) sphygmomanometry and oscillometry, applied at the ventral coccygeal artery were compared with simultaneous direct blood pressure measurements at the dorsal pedal artery in 10 anesthetized, captive cheetahs (Acinonyx jubatus). The DOP method was moderately accurate, with relatively little bias (mean difference 3.8 mmHg) and 88.6% of the DOP systolic arterial pressure measurements being within 10 mmHg of the direct systolic arterial measurement. With the oscillometric (OM) method, 89.2% of the mean arterial pressure measurements were within 10 mmHg of the direct measurement and had the least bias (mean difference 2.3 mmHg), 80.7% of the systolic measurements were within 10 mmHg of the direct measurement and had the second least bias (mean difference 2.3 mmHg), and 59% of the diastolic measurements were within 10 mmHg of the direct measurement and had significant bias (mean difference 7.3 mmHg). However, DOP showed relatively poor precision (SD 11.2 mmHg) compared with OM systolic (SD 8.0 mmHg), diastolic (SD 8.6 mmHg), and mean (SD 5.7 mmHg). Both techniques showed a linear relationship with the direct technique measurements over a wide range of blood pressures. The DOP method tended to underestimate systolic measurements below 160 mmHg and overestimate systolic measurements above 160 mmHg. The OM method tended to underestimate mean pressures below 160 mm Hg, overestimate mean pressures above 160 mmHg, underestimate systolic pressures below 170 mmHg, overestimate systolic pressures above 170 mmHg, and underestimate diastolic pressures throughout the measured blood pressure range. Indirect blood pressure measurement using the ventral coccygeal artery, particularly when using an OM device for mean and systolic arterial pressure, may be useful in the clinical assessment of cheetahs when monitoring trends over time, but caution should be taken when interpreting individual values.

Estudo da pressão arterial pelo método indireto oscilométrico (petmap®) em cães domésticos não anestesiados

O estudo das pressões arteriais sistólica, média, diastólica e da frequência cardíaca, pelo método indireto oscilométrico (petmap®), foi realizado em 150 cães atendidos pelo Serviço de Clínica Médica de Pequenos Animais da FMVZ - Unesp/Botucatu. Investigou-se a influência de fatores como presença do proprietário, estado de saúde, diagnóstico de doença renal, raça, idade, sexo, decúbito, contenção, fluidoterapia, condição corpórea, temperamento, atividade física, dieta e atitude associados ou não à elevação da pressão arterial. Dos 150 cães, 34% encontravam-se sob a categoria de risco mínimo para o desenvolvimento de lesões hipertensivas, 14,6% com hipertensão branda, 22,6% com hipertensão moderada e 28,66%, com hipertensão grave. Houve influência, dos fatores analisados, na elevação da pressão arterial de acordo com a categoria de risco.

Renal programming: cause for concern?

Development of the kidney can be altered in utero in response to a suboptimal environment. The intrarenal factors that have been most well characterized as being sensitive to programming events are kidney mass/nephron endowment, the renin-angiotensin system, tubular sodium handling, and the renal sympathetic nerves. Newborns that have been subjected to an adverse intrauterine environment may thus begin life at a distinct disadvantage, in terms of renal function, at a time when the kidney must take over the primary role for extracellular fluid homeostasis from the placenta. A poor beginning, causing renal programming, has been linked to increased risk of hypertension and renal disease in adulthood. However, although a cause for concern, increasingly, evidence demonstrates that renal programming is not a fait accompli in terms of future cardiovascular and renal disease. A greater understanding of postnatal renal maturation and the impact of secondary factors (genes, sex, diet, stress, and disease) on this process is required to predict which babies are at risk of increased cardiovascular and renal disease as adults and to be able to devise preventative measures.

Evaluation of an indirect oscillometric blood pressure monitor in normotensive and hypotensive anesthetized dogs

OBJECTIVE

To determine the accuracy and precision of an oscillometric noninvasive blood pressure device as a predictor of invasive direct blood pressure in healthy anesthetized hypotensive and normotensive dogs.

DESIGN

Prospective observational study.

SETTING

University teaching hospital.

ANIMALS

Eight crossbred adult dogs.

INTERVENTIONS

Anesthesia was induced with propofol and maintained with isoflurane. A catheter was placed in the dorsal pedal artery to record systolic, mean, and diastolic arterial blood pressures (aSAP, aMAP, and aDAP, respectively). The noninvasive blood pressure device cuff was placed around the contralateral front limb to record noninvasive systolic, mean, and diastolic blood pressure (nSAP, nMAP, and nDAP). Two states of blood pressure (BP) were studied: baseline state was established by keeping end-tidal isoflurane concentration at 1.2+/-0.1%. The hypotensive state was achieved by maintaining the same isoflurane concentration while withdrawing approximately 40% of the animal's blood volume until aMAP was stable at approximately 40 mm Hg. At the end of the study, blood was returned to the animal and it was allowed to recover from anesthesia.

MEASUREMENTS AND MAIN RESULTS

Agreement between the direct and indirect BP measurements was determined by the Bland-Altman method. The SAP and MAP but not DAP bias varied significantly between each BP state. Normotensive absolute biases (mean [SD]) for SAP, MAP, and DAP were -14.7 mm Hg (15.5 mm Hg), -16.4 mm Hg (12.1 mm Hg), and -14.1 mm Hg (15.8 mm Hg), respectively. Absolute biases during the hypotensive state for SAP, MAP, and DAP were -32 mm Hg (22.6 mm Hg), -24.2 mm Hg (19.5 mm Hg), and -16.8 mm Hg (17.2 mm Hg), respectively.

CONCLUSION

The oscillometric device was not reliably predictive of intra-arterial BP during hypotension associated with acute hemorrhage.

Development of hypertension and effects of benazepril hydrochloride in a canine remnant kidney model of chronic renal failure

In order to determine whether hypertension would develop in dogs with chronic renal failure, we performed 7/8 renal ablation in 6 healthy dogs and compared pre- and post-ablation blood pressures determined by telemetry. One month after the renal ablation, blood urea nitrogen and creatinine were significantly increased (p<0.05), creatinine clearance was decreased (p<0.05), and blood pressure was increased significantly (p<0.05). Simultaneously, plasma renin activity, angiotensin I and II, and aldosterone were elevated significantly (p<0.05) compared with the values obtained from 11 healthy dogs with intact renal function. The dogs with induced renal failure and hypertension were administered an angiotensin-converting enzyme inhibitor, benazepril hydrochloride, once daily for 2 weeks at 2 mg/kg body weight, and changes in blood pressure and the renin-angiotensin-aldosterone (RAA) system were determined. During the administration of benazepril hydrochloride, blood pressure, angiotensin II and aldosterone decreased significantly (p<0.05) and, upon discontinuation of administration, increased to the pre-administration levels (p<0.05). Plasma renin activity and angiotensin I showed no significant changes throughout the administration study. These results provide experimental evidence that hypertension develops in dogs with chronic renal failure through mechanisms involving the RAA system and demonstrate that benazepril hydrochloride improves renal hypertension in dogs.

Determination of reference arterial blood pressure values by indirect methods for Kangal dogs

OBJECTIVES

To obtain reference arterial blood pressure values from Kangal dogs, a local giant breed found in Turkey.

METHODS

Arterial blood pressure measurements were obtained from 48 healthy Kangal dogs using oscillometric and Doppler techniques. The ages of the dogs ranged from two to 96 months, with a mean (sd) age of 36 (16) months.

RESULTS

The effect of age on systolic, diastolic and mean arterial pressures determined by the oscillometric technique and on systolic pressure determined by the Doppler technique was significant (P<0.001). Blood pressure was found to be higher in mature dogs compared with that in immature dogs. The effect of sex and the interaction between age and sex were not significant (P>0.05). There was a direct relationship between age and oscillometric systolic, diastolic and mean arterial pressures and Doppler systolic arterial blood pressure both in the whole group and the immature group (P<0.05). Correlation between age and systolic arterial blood pressure measured either by oscillometric or Doppler techniques was not significant in the mature group.

CLINICAL SIGNIFICANCE

The Kangal dog is bred in various countries including Turkey. It is known that giant breed dogs, such as the Kangal dog, are predisposed to cardiovascular disease. Canine arterial blood pressure values are highly breed and age dependent, so a reference value for any other breed is inappropriate for Kangal dogs. Therefore, it is important to measure arterial blood pressure of Kangal dogs.

Relationships Between Degree of Azotaemia and Blood Pressure, Urinary Protein:Creatinine Ratio and Fractional Excretion of Electrolytes in Dogs with Renal Azotaemia

Blood pressure (BP) was measured in 31 renal azotaemic dogs by oscillometric measurement at the posterior tibia artery, and urine and blood samples were collected. Haematology, blood chemistry and urinalysis were performed and urinary protein:creatinine ratio (UPC) and fractional excretions of electrolytes (FE(e)) were calculated. The results showed that only 19% of dogs with renal azotaemia were hypertensive, whereas almost all of them had high urinary protein and electrolyte excretions. There was no association between BP, UPC and FE(e). A positive correlation was found between all pairs of electrolyte fractional excretions. When the severity of renal impairment was observed using plasma creatinine concentration, neither BP nor UPC was correlated. Only the FE( e ) was associated with the degree of azotaemia. The results suggest that dogs with renal azotaemia do not necessarily have hypertension. The fractional urinary excretion of electrolytes may be a good indicator for severity of renal dysfunction in azotaemic dogs.

Diurnal variations of blood pressure in dogs

Using the telemetry system, we measured the blood pressure (BP) invasively in seven adult mongrels while unanesthetized and unbound. Post-operative BP after implanting the telemetry BP transmitter showed temporarily high values due to the invasive nature of the surgery. It was, however, observed that BP gradually decreased thereafter, and showed settled trends from the eighth day post-operatively. When we took the average of the systolic, mean and diastolic BP at hourly intervals for each of the dogs once their BP had settled, a twin peak diurnal variation (at 8:00 and 19:00) was observed. Moreover, significantly high values (p < 0.05) were identified in active state compared with when sleeping or at rest. The 24 hr BP measured by the telemetry system in seven normal dogs resulted in the following values: systolic 123.4 +/- 7.9 mmHg, mean 91.1 +/- 5.6 mmHg, and diastolic 74.5 +/- 4.9 mmHg.

Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with chronic renal failure

The systolic, mean and diastolic pressures as well as the heart rate were measured using the oscillometric method, on a total of 104 cats (60 cats in the normal group, and 44 in the renal disease group) which were brought into Azabu University Animal Hospital. The blood pressure in the normal group was systolic: 115.4 +/- 10.1 mmHg, mean: 96.2 +/- 12.2 mmHg, and diastolic: 73.7 +/- 10.7 mmHg. Although no difference in heart rate, the renal disease group showed significantly (p < 0.05) higher values for systolic, mean, and diastolic pressure when compared with the normal group. Moreover, when plasma renin activity, angiotensin I and II, and aldosterone concentrations were measured in other cats (11 normal and seven with chronic renal failure), all cats with chronic renal failure showed significantly (p < 0.05) higher values than the normal group. It is, therefore, indicated that hypertension due to stimulating renin-angiotensin-aldosterone system may have manifested in cats with renal dysfunction.